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It's no secret that smoking and heavy drinking take a toll on the body, but University of Iowa researchers have found that tobacco and excessive alcohol use accelerates aging in a way that can be measured in a person's DNA.

Using new methods of DNA analysis, the researchers found that all levels of exposure to smoke, as well as high alcohol consumption, were associated with significantly premature aging.

UI's Dr. Robert

study, which analyzed information culled from from a massive public gene database.

"People talk about the idea that smoking probably accelerates your aging, but we're probably the first to demonstrate it actually does," said Dogan, who presented the findings this week at the American Society of Human Genetics' annual conference in Baltimore.

While the researchers linked faster aging to heavy drinking, they found that, conversely, moderate alcohol consumption — about one or two drinks a day — was correlated with the healthiest aging.

Whether moderate alcohol use actually slows down aging, or is merely associated with it, remains unclear, the researchers said.

The UI scientists have also developed a method of using DNA markers to pinpoint just how much a person smokes or drinks, providing a new way to objectively monitor consumption, regardless of whether a person discloses their substance use.

"It won't come as a big surprise that when you ask people how much they drink, it's totally unreliable," Philibert said. "We don't have to ask anymore — we can exactly measure your consumption.

"And best yet, there's no way you can hide from it. It can see through any drug, any type of camouflage you can come up with, and because it's DNA based, we know it's you."

Using the gene database, the researchers analyzed patterns of DNA methylation — a molecular modification to DNA that affects when and how strongly a gene is expressed. Research has shown that methylation changes in predictable ways as people age, and environmental exposures, such as cigarette smoke and alcohol, can also change the patterns.

Looking at changes in two specific locations in the genome where methylation levels are highly associated with smoking and alcohol consumption, the researchers were able to determine a person's "biological age" and compare it to their actual "chronological age," then assess the role tobacco and alcohol played.

Being able to measure alcohol and tobacco consumption objectively could be a useful tool for insurance companies, Philibert said. It could also help in policy research, particularly in studies examining the relationship between lifestyle choices and health outcomes, he said.